In U.S. Ser. No. 09/520,437 now U.S. Pat. No. 6,242,145, filed Mar. 7, 2000, entitle xe2x80x9cTONER AND DEVELOPER PROVIDING OFFSET LITHOGRAPHY PRINT QUALITYxe2x80x9d there is disclosed a developer of a mixture of carrier particles and toner particles containing at least one binder, at least one colorant, and optionally one or more additives, has a triboelectric value of from 35 to 60 xcexcC/g, a charge distribution (Q/D) of from xe2x88x920.5 to xe2x88x921.0 fC/micrometer and the distribution is substantially unimodal and possesses a peak width of less than 0.5 fC/micrometer, preferably less than 0.3 fC/micrometer, and a conductivity of the developer ranges from 1xc3x9710-11 to 10xc3x9710-15 mho/cm as measured at 30 V. The carrier particles of the developer preferably have an average particle diameter of 65 to 90 microns and a size distribution wherein 2.0% or less of a total number of carrier particles have a size less than 38 micrometers. The ratio of carrier volume median diameter to toner volume median diameter is about 10:1. The developer finds particular use in devices utilizing hybrid scavengeless development. Use of a developer with such properties in a hybrid scavengeless development apparatus enables images to be achieved with properties similar to that achieved in offset lithography.
In U.S. Ser. No. 09/520,361 now U.S. Pat. No. 6,248,496, filed Mar. 7, 2000, entitled xe2x80x9cMETHOD OF REPLENISHING DEVELOPER IN A HYBRID SCAVENGELESS DEVELOPMENT SYSTEM,xe2x80x9d there is disclosed a replenisher material of toner particles and carrier particles, wherein a replenisher ratio of the toner particles to the carrier particles in the replenisher is determined as a function of at least one property of the developer and at least one operational property of an apparatus for developing an electrostatic latent image recorded on an image receiving member, and wherein the apparatus includes a housing defining a chamber having a supply of developer comprised of toner particles and carrier particles therein, a donor member spaced from the image receiving member and adapted to transport toner particles of the developer from the chamber to a development zone adjacent the image receiving member, at least one wire positioned in the development zone between the image receiving member and the donor member, a voltage supply for electrically biasing the at least one wire during a developing operation with a current to detach toner particles from the donor member, forming a cloud of toner particles in the development zone, and developing the latent image with toner particles from the cloud, and at least one dispenser for dispensing replenisher comprised of toner particles and carrier particles into the chamber, wherein a replenisher ratio of the toner particles to the carrier particles in the replenisher is determined as a function of at least one property of the developer and at least one operational property of the apparatus. The replenisher ratio is preferably determined as a function of the tribo stability of the developer in a non-replenishment mode of the apparatus and/or as a function of the conductivity of the developer in a non-replenishment mode of the apparatus.
The disclosures of each the above mentioned copending applications are incorporated herein by reference in their entirety. The appropriate components and processes of these patents may be selected for the toners and processes of the present invention in embodiments thereof.
This invention relates generally to apparatus and method for controllably and accurately melt mixing, for example in an extruder, two or more resin materials to produce a product with a desired combination of properties. More specifically the present invention relates to an apparatus and method for controllably and accurately melt mixing a mixture of two or more resins, in real-time, while continuously monitoring the melt rheology properties of the melt mixture, such as the viscosity, the elasticity, or both, and adjusting, if necessary, the ratio of feed mixture resin materials, so that the resulting product mixture will possess highly specific and desirable properties, for example, a narrow glass transition temperature (Tg) range, melt viscosity and elasticity, a narrow image gloss value within a wide range of possible gloss values, and wherein the fuser roll life is enhanced or extended. The invention, in embodiments, can be accomplished by combining in an extruder apparatus, a mixture of two or more thermoplastic resins, or related resin materials, including cross-linked resin or resin blends, and continuously monitoring the melt rheology of the resulting mixture in the extruder. The apparatus and method of the present invention, alternatively or additionally, solves several problems and provides various advantages including, for example: co-feeding toner reclaim fines to minimize the variation of toner rheology associated with different lots of resin feed or reclaim materials and for different concentrations of toner reclaim fines.
Problems associated with controlling melt mixture rheology, and the properties of the melt blend can depend, for example, upon the desired or required properties of the resultant mixture, for example, a toner imaging material.
Toner is the image-forming material in a developer which when deposited by the field of an electrostatic charge becomes the visible record. There are two different types of developing systems known as one-component and two-component systems. In one-component developing systems, the developer material is toner comprised of particles of magnetic material, usually iron, embedded in a black plastic resin. The iron enables the toner to be magnetically charged and developed. In two-component systems, the developer material is comprised of toner of polymer or resin particles and a colorant, and a carrier of roughly spherical particles or beads usually made of steel. An electrostatic charge between the toner and the carrier bead causes the toner to cling to the carrier in the development process and to be subsequently transferred to a charged latent image on an imaging member such as a photoreceptor.
In U.S. Pat. No. 5,650,484, issued, Jul. 22, 1997; to Hawkins, et al., there is disclosed an apparatus for the preparation of a mixture of toner resin and initiator, to form a toner resin or toner mixture including cross-linked micro-gel particles is provided. The apparatus includes a toner extruder having the resin being conveyed therethrough and an adder for adding the initiator to the toner resin in the toner extruder to form the toner resin or mixture. The apparatus also includes a measurer for measuring the cross-linked micro-gel particles in the toner mixture substantially immediately after mixing in the toner extruder and transmitting a signal indicative of the quantity of cross-linked micro-gel particles in the toner resin or mixture. The apparatus also includes a controller for controlling the addition rate of initiator in response to the signals from the measurer.
Other references of interest include: U.S. Pat. Nos. 4,141,252 and 4,454,765, which disclose a devices for measuring melt rheological properties of, for example, resin and resin mixtures, and as discussed below.
There remains a need for simple, efficient, safe, economical, and highly reliable and reproducible method and apparatus for monitoring, analysis, and real-time manipulation of the in situ, that is within the extruder or melt mixing device itself, melt rheological properties of a blend of two or more resin constituents, for example in a toner extrusion process, and the like industrial or specialty formulations.
Embodiments of the present invention, include:
Overcoming or minimizing problems encountered in the art by providing melt mixing process equipment and methods, which enable improved manufacturing efficiency and improved reliability of the properties of the resulting melt blended resin materials;
A process comprising:
introducing and continuously melt mixing in an extruder a mixture of a first resin feed and a second resin feed;
measuring within the extruder the melt rheology of the resulting melt mixture of the first and second resins;
determining the relative ratio of the first resin and a second resin from the melt rheology in the resulting melt mixture; and
adjusting the relative feed ratio of the first resin and second resin feeds introduced to the extruder; and
A process comprising:
continuously melt mixing a mixture of two or more feed resins in an extruder;
continuously measuring the melt rheology in viscosity or elasticity of the resulting resin melt mixture within the extruder;
continuously computing the relative ratio of the resulting resin mixture from the measured melt rheology; and
altering the relative ratio of the feed resins introduced to the extruder if the relative ratio of the resins in the resulting melt mixture, as measured by the melt viscosity or elasticity of the mixture near the extruder exit port, deviates from a predetermined melt viscosity of, for example, about 2,400 poise at 30 secxe2x88x921 per 125xc2x0 C. by more than about 40 to about 45 units as measured by a Goettfeit viscometer, and melt elasticity of, for example, 3,100 dynes/cm2 per 135xc2x0 C. by more than about 75 to about 80 units as measured by a Lodge Stressmeter(copyright).
These and other aspects are achieved, in embodiments, of the present invention as described and illustrated herein.